The invention relates to a seal for sealing joints between a higher-pressure space and a lower-pressure space on parts and components to be sealed off, in particular on ducts or conduits comprising concrete pipes and shaft structures.
A seal a primary seal in the form of a taper sliding ring and a comprising secondary seal in the form of an axially projecting annular bead with a high degree of flexibility, is known from U.S. Pat. No. 3,417,942 Jornhagen subdivided in a latticework-like fashion and which has air-filled cavities without an outlet opening. The taper sliding ring is carried on the cylindrical surface of the spigot end of a pipe while the annular bead is disposed on the radial front face of that spigot end. Upon assembly with the socket end of a pipe, the socket slides over the inclined surface of the taper sealing ring and compresses it so as to afford a pressure profile with a rising pressure flank. The annular bead as the secondary seal is compressed to a greater or lesser degree when the pipes are fitted together, the pressures which occur in that situation being low because otherwise the pipes are pushed apart by that pressure. Accordingly, the sealing action with annular bead seals is not very great, and not adopted for a relatively great pressure drop. When using taper sliding rings as the primary seal, the sealing action depends on the width of contact and the surface pressure, which in turn are very heavily dependent on the production tolerances of the pipes which are to be fitted one into the other, such tolerances determining the width of the gap which is to be sealed off. If the gap is of great width, then the sealing width is small and the contact pressure is low while a narrow gap means that the sealing width and the contact pressure admittedly become high, but the risk of the seal being squashed or the risk of cracks being formed in the socket of the pipe or the spigot end thereof can become great.
U.S. Pat. No. 522,413 discloses a seal for sealing the expansion gap between concrete portions. The seal includes so-called chevron walls which, by virtue of their Y-shaped configuration, bend slightly and guarantee an approximately uniform contact pressure, irrespective of the width of the gap. It is not possible to provide sealing integrity between a high-pressure space and a low-pressure space.
Seals with a cavity as a pressing means are known per se (German Provisional Applications 38 15 142 and 42 36 368). In such an arrangement, a cavity disposed in the seal body is charged with liquid, possibly setting pressing agent under high pressure, small pipe portions of which are passed through the precast concrete parts being used for that purpose. The cavity cannot be used as a test space to establish sealing integrity of the seal.
It has long been known for expansion joint seals to be provided with cavities which by virtue of high internal pressure result in an increased contact pressure on the part of the seal (German published application 551 816).
Arranging slide lugs on the inclined surface of sliding seals is known from Germany published Application No. 36 01 757.